We propose the application of new methods for the production and characterization of antisera against human leukemia associated antigens. This involves the use of somatic cell hybrids between mouse cells and human leukemia cells. These hybrids will be used to produce antisera against human leukemia-associated antigens and for genetic linkage analysis of the loci determining these tumor antigens. The antisera will be used for biochemical analysis of human leukemia antigens, to determine the role these antigens play in cell mediated immunological reactions, and to define the possible distribution of these antigens on fetal cells or minority populations of normal adult cells.